Electric induction machine



May 28, 1946. D. c. PRINCE 2,401,187

ELECTRIC INDUCTION MACHINE Filed March 1, 1945 Figl; Fig.3

Fig.5.

Inventor: David C- FTince,

vb W

Hrs Attorney.

Patented May 28, 1946 2,401,187 ELECTRIC INDUCTION MACHINE David 0. Prince, Schenectady, N. Y., assignor to General Electric Company, a corporation of- New York Application March 1, 1943, Serial No. 477,511

2 Claims.

My invention relates to electric induction ma-' chines such as induction clutches, brakes, and dynamometers.

An object of my invention is to provide an improved electric induction machine having provision for improved use of material and an efiicient cooling system.

Further objects and advantages of my invention will become apparent and my invention will be better understood from the follow'ingdescription referring to the accompanying drawing,- and the features of novelty which characterize my invention will be pointed cut with particularity in the claims annexed to and forming part of this specification.

In the drawing, Fig. 1 is an end elevational view, partly broken away, of anelectric induction machine provided with an embodiment of my invention; Fig. 2 is a side elevational view, partly in section, of the machine shown in Fig. 1; Fig. 3 is a plan view of a part of the electromagnet of one of the members shown in Figs. 1 and 2; and Fig. 4 is a sectional view through an electromagnet adapted to be used in a construction similar to that shown in Fig. 2 in which the core is formed of two separable members instead of a single integral member.

Referring to the drawing, I have shown a embodiment of my improved electric induction machine provided with. two relatively rotatable members, one of which is arranged within the other and provided with a supporting spider In mounted upon a shaft II. The spider I is provided with a rim l2 to which a core 13 of magnetic material is secured by bolts H, or in any other suitable manner. The core i3 forms part of a substantially circular electromagnet provided with a field exciting winding 15 wound about the core l3 and insulated therefrom by a covering of insulation IS. A plurality of inter digitated pole pieces I! and i8 of alternately opby bolts 2!, or in any other suitable manner. This construction may preferably be used where it is desired to provide a relatively large section of magnetic material in the pole pieces, and also enables the use of a preformed coil which can be inserted between the core and the pole pieces.

' act electrodynamically with another member provided with a core formed of axially spaced posite polarity extends from opposite sides of the core 13. This electromagnet may be formed with a unitary core and pole member, in which casethe pole pieces I] and i8 are formed to extend radially outwardly from the central core portion l3 until after the coil I3 is wound in place and then the pole pieces are bent over the outer periphery of the coil l5, as shown in Fig. 3. The electromagnet also might be formedas shown in Fig. 4, in which case the central core I3 is formed integral with pole pieces l3 to provide a substantially U-shaped'section member, and a. substantially L-shaped care member including pole pieces 20 is secured to the central core I! apart substantially annular plates of magnetic material arranged about the electromagnetic member pole pieces. A double squirrel cage winding is arranged in this core and includes two sets of electrical conductors 26 and 21 extending through the plates 25 with a member 28 of electrically conductive material at each end of the core spaced therefrom and electrically connected to the conductors 26 and 21 providing a short-circuiting connection between these conductors. One set of the conductors 26 is arranged relatively close to the inner peripheryof the core formed by the plats 25 and adjacent the electromagnetic member, while the other set of electrical conductors 21 is arranged relatively further from the inner periphery of the core. With such an arrangement, the inductive reaction due to the variations in the linkages of the magnetic lines of force from the rotatable electromagnetic member with the conductors 26 and 21 is efficiently utilized over a wide range of speed, as the arrangement of the conductors in the two squirrel cages provides for a maximum linkage with the magnetic lines of force for different penetrations into the core formed by the plates 25,

The squirrel cage member including the squirrel cage windings and the core formed by the plates 25 is supported by a frame including end plate sections 29 and 30 which are spaced apart by arms 3| and are secured together by a pluv ralityof bolts 32, or in any other suitable manner. The core and winding are mounted in the frame by a plurality of bolts 33 which extend through insulating bushings 34 and are secured to ears 35 formed on the plates 28. The frame end sections are provided with hearing housing hubs 33 arranged about bearings 31 which rotatahly support the electromagnetic member in a relatively rotatable relationship to the squirrel cage member. With this construction, rotation of the electromagnet produces a tan effect which blows ventilating air outwardly between the core plates 25 and efllciently cools these-plates and the conductors 2B and 21. The conductors form a tight lit with openings in the plates 25 to provide a good thermal connection thereto such that heat generated in the conductors by electric currents is readily transferred to the plates 25, and these plates act as-radiating flns which further provide for eillciently cooling the squirrel cage member. The end sections 29 and 30 are formed with relatively large openings therein, and the spacing arms Ii provide relatively large exhaust openings therebetween to provide tor a maximum and emcient now of ventilating medium through the machine. Such a machine may be used as a clutch, brake, or dynamorneter, and in each case would be provided with a suitable connection to the trame oi the squirrel cage member and to the shaft or the electromagnetic member to'transmit torques between these members and external mechanical connections.

While I have illustrated and described a particular embodiment of my invention, modifications thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangement disclosed, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent oi! the United States is:

1. An electric machine having a member with an electromagnet provided with interdigitated pole pieces oi! alternately opposite polarity, a second member arranged to react electrodynamically with said first member and having a core formed or axially spaced apart plates of magnetic material arranged around said electromagnetic member, and a squirrel cage winding in said core formed or electrical conductors extending through said plates with a member of electrically conductive material at each end of said core connected to said conductors, said interdigitated pole pieces being arranged within said plates to provide a fan eifect for impelling ventilating medium outwardly between said plates whereby ventilating medium is circulated directly over said plates and said squirrel cage electrical conductors tor cooling the same.

2. An electric machine having a member with an electromagnet provided with interdigitated pole pieces of alternately opposite polarity, a second member arranged to react electrodynamically with said first member and having a core formed of axially spaced apart plates of magnetic material arranged around said electromagnetic member, a double squirrel cage winding in said core formed or two sets of electrical conductors extending through said plates with a member of electrically conductive material at each end of said core connected to said conductors, one of said sets of conductors being arranged relatively close to the inner periphery of said core and the other of said sets or conductors being arranged relatively further from the inner periphery of said core, means including end plates for supporting said core 01' axially spaced apart plates. and means for supporting said electromagnetic member in relatively rotatable relation to said second member, said interdigitated pole pieces being arranged within said plates to provide a i'an effect for impelling ventilating medium outwardly between said plates whereby ventilating medium i circulated directly over said plates and said squirrel cage electrical conductors for cooling the same.

DAVID c. PRINCE. 

